Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)




Chronic low back pain (CLBP) is a prevalent condition, often involving an inflammatory process. Those with CLBP frequently experience behavioral symptoms, including depressed mood, fatigue, and sleep disturbance, which may exacerbate pain and reduce quality of life (QOL). The purpose of this study was to identify behavioral symptom clusters (depressive mood, fatigue, poor sleep) in individuals with CLBP, and to determine whether there are differences in pain, QOL and inflammation (plasma IL-6) based on cluster membership. CLBP patients (N=69; age = 56±13 years) completed measures of pain, depressive mood, fatigue, sleep, and QOL. Blood was obtained for IL-6 measurement. LCA revealed a two-class model. Participants in Class 1 characterized by High Behavioral Symptoms (HBS) had more depressive mood, fatigue, and sleep disturbance (including less sleep per night) compared to participants in Class 2 characterized by Low behavioral Symptoms (LBS). Univariate general linear models revealed HBS reported worse QOL and pain interference than those in LBS. Pain severity did not significantly differ between the classes. Exploratory analysis suggested this was due to a moderating effect of IL-6 on pain severity. Levels of IL-6 (controlling for BMI) were trending to significantly greater in HBS, compared to LBS, with higher levels of IL-6 correlating with greater pain severity and more sleep disturbance. Further, logistic regression revealed higher levels of IL-6 predicted HBS membership. In conclusion, behavioral symptoms cluster in individuals with CLBP and worsen QOL. Inflammation contributes to the complex relationship between behavioral symptoms and pain severity. Clinical recognition of behavioral symptom clusters can foster more comprehensive pain assessment and tailored interventions for CLBP patients.

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Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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